The National Weather Service says wind is the main threat from storms forming in eastern Oklahoma and into western and central Arkansas, though some flash flooding is also possible.
The weather service said Sunday that the threat would continue into the night and persist into Monday morning.
A flash flood watch was in place Sunday in northeast Oklahoma and much of northern Arkansas.
Thunderstorm chances are forecast to decrease Monday and Tuesday, especially in Oklahoma. A weak frontal boundary will bring increased storm chances by the middle of the week into the weekend.
Hot and humid conditions are in store for the week ahead. Heat index values in the triple digits will be common in places.